Research On The Mechanical Performance Of Castellated Portal Frame

As a new type of steel structure,the castellated steel portal frame has many advantages such as light weight,high bearing capacity,reasonable cross-sectional shape,economy,aesthetics,and application.It has been widely used in many countries,and many countries have developed relevant standard code to guide the design of castellated portal beam and column members.The current specifications in our country only specify the seismic design of ordinary steel portal frame,there is no corresponding specification standard for castellated steel portal frame.At present,the research results of many scholars or institutes in our country and others are mostly focused on the research of castellated beams,castellated columns or castellated portal frame nodes.However,the research on the mechanical performance of the overall mechanical performance of the castellated steel portal frame is relatively small.Moreover,due to the diversity of structural shapes of castellated steel structure,the factors that affect the overall performance of the castellated portal frame are very simple and not comprehensive.This largely restricts the development of the castellated steel portal frame rigid frame system,so it is especially important to carry out various stresses performance studies.In this dissertation,according to the different expansion ratio of the castellated portal beam,the distance from the first hole of the beam to the end plate of column,and the connection method of the column base,we using the finite element software ABAQUS to carry out the beam concentrated load and uniform load distribution respectively on the castellated portal frame.The simulation analysis under column-top horizontal cyclic load is to explore and summarize its various mechanical properties.Through research conclusion are drawn as follows:(1)Static analysis conclusions:(1)Most of the failure of the castellated portal frame are occurs at the base of the column,the first hole at the beam end and the beam-column node domain.(2)Compared with the original model,under the vertical static load,the castellated portal frame has greater bearing capacity.When the expansion ratio is less than 1.35,the yield load and ultimate load of the castellated model increase with the expansion ratio.On the contrary,when the expansion ratio is greater than 1.35,the yield load and ultimate load of the model decrease with the expansion ratio.After the expansion ratio exceeds 1.45,the reduction of the yield load and ultimate load of the model is more obvious.(3)On the first hole at the beam end,the concentrated load has a greater influence than that of uniform load.(2)Seismic performance analysis conclusions:(1)Under horizontal cyclic loading,the yield load and ultimate load of the castellated portal frame are greatly increased compared with the original portal frame.When the expansion ratio is less than 1.4,the model yield load increases with the beam expansion ratio and the ultimate load increases gradually.When the expansion ratio is greater than 1.45,the ultimate load of the model decreases with the increaseof the expansion ratio.The bearing capacity of the castellated portal frame is the highest when the expansion ratio is between 1.3 and 1.4.(2)The expansion ratio of the castellated beam has little effect on the lateral stiffness of the castellated portal frame,but it has a great influence on ductility and energy consumption.(3)The bolt connection of the castellated portal frame column base greatly weakens the lateral stiffness of the castellated portal frame.